The problem isn't with the technology (newsletters vs. blogs) but with the way the technology's being used. Newsletter creators learned long ago that it made much more sense to send out tightly-focused newsletters, something that many bloggers have yet to learn. Those bloggers cast too wide a net and turn off some of their readers.

One way to just get the things that interest you from a less-focused blog is to use category feeds if the blogging software supports it. This relies, of course, on the blogger properly and consistently categorizing his or her posts, but it can definitely narrow things down.